Liquid heating vessels

ABSTRACT

A control for engagement with the external base of a liquid heating vessel comprises a carrier mounting two bimetallic actuators at opposite ends thereof. The actuators operate at the same temperature. Attached to the carrier is a moulding which provides a cordless electrical connector for the vessel, as well as mounting switch means operable by the actuators through push rods. The push rod acts on a leaf spring to open the contacts, and upon further movement engages an arm of a trip lever, so tripping the lever and causing a further arm of the lever to engage the leaf spring open the contacts fully.

The present invention relates to liquid heating vessels havingelectrical heating elements, and in particular in certain aspects toliquid heating vessels having a liquid receiving container and anelectrical heating element secured in good thermal contact to theunderside of the container. An example of such an arrangement is shownin GB-A-2042269.

Such types of vessel are popular in certain areas of the world, forexample in continental Europe, for boiling water for making hotbeverages such as tea and coffee. Typically, the liquid receivingcontainer has a base portion at least which is made from a corrosionresistant metal such as stainless steel, which gives the interior of thevessel an attractive appearance and makes it easier to clean. The restof the vessel may also be of this metal, but could possibly also be offor example a plastics material suitably joined to the base portion. Thecontainer conventionally has an external base plate made of a highthermal conductivity metal such as aluminium, to which the element issecured and through which heat is conducted into the container.

It has been common in such vessels to provide thermally sensitiveoverheat protection means in thermal contact with the element of thevessel which operates to interrupt or reduce the supply of electricalenergy to the element in the event of the element overheating, as mighthappen if the vessel boils dry or if it is switched on without anyliquid in it. Typically such overheat protection means comprises athermally sensitive switch, mounted on the base plate of the vessel,which operates to open a set of contacts in the electrical supply to theelement. The switch may, for example, comprise a bimetallic actuator,and be such as to reset automatically upon the container cooling down.Some vessels may also be provided with a one-shot device such as athermal fuse arranged under the base, which senses a dangerousoverheating of the vessel and must be replaced after it operates.

The problem with existing controls of this type is that the temperatureof the container base, and thus indirectly the temperature of theelement, is sensed effectively only at a single location on the base.Thus if, for example, the vessel is accidentally placed on a worksurface so that its base slopes, it is possible that as the vessel boilsdry one part of the bottom of the container may still be covered bywater, but another be uncovered. This part of the base will thereforeoverheat first, and if the overheat protecting means is arranged underthe part of the vessel base still covered with water, severe overheatingof the element may occur locally, which is potentially very dangerous.

The invention from one aspect seeks to provide an improved vessel of theabove type.

From a first aspect therefore, the invention provides a liquid heatingvessel comprising: a liquid receiving container; an electrical heatingelement provided on or in thermal contact with the base of saidcontainer; a thermally sensitive overheat control arranged to operate inthe event of said element overheating so as to interrupt or reduce thesupply of electrical energy to the element; said thermally sensitiveoverheat control comprising at least two thermally responsive sensorsarranged in good thermal contact with, and at spaced apart locations on,the base of the container or the element, said sensors individuallybeing operable, in the event of said element overheating so as tointerrupt or reduce the supply of electrical energy to the element.

Thus in accordance with the invention, at least two thermally responsivesensors are provided in close thermal contact with the base of thevessel container, which will allow the temperature of the base andelement to be detected accurately at at least two spaced apart locationsso that should the base or element overheat locally, at least one of thesensors may sense this quickly and operate to interrupt or reduce thepower supply to the element, for example opening a set of electricalcontacts remote from the sensor through suitable actuating means.

Preferably in order to achieve consistent operation of the control, thesensors are chosen to have substantially the same operating temperaturecharacteristics. However, this is not essential, and one sensor mayoperate at a higher temperature than the other. This is not preferred,however, since depending on the location of the sensors, overheating ofthe vessel may occur in certain operating conditions.

To obtain optimal thermal transfer from the container base to thesensors, they are preferably mounted directly against the container baseor element. Also, to obtain a good response, the sensors should bespaced apart by a substantial distance.

This is advantageous in that it will allow the depth of the basecompartment to be minimised, thereby reducing the overall height of thevessel, contributing to the stability of the vessel and enhancing itsappearance.

The term sensor as used above is intended to be interpreted broadly andmay cover a number of different constructions. For example it mayinclude electrical or electronic temperature sensors, but preferably thesensors comprise thermo-mechanical actuators, most preferably bimetallicactuators. Such actuators are well known in the art, and typicallyproduce an actuating movement with a snap action upon reaching apredetermined temperature.

From a second aspect, the invention provides a thermally sensitiveoverheat control for mounting to the base of a liquid heating vessel andarranged to operate in the event of said element overheating so as tointerrupt or reduce the supply of electrical energy to the element; saidthermally sensitive overheat control comprising at least two thermallyresponsive bimetallic actuators mounted on a face of said control atlaterally spaced apart locations thereon, for engagement with the baseof the container or the element, said sensors individually beingoperable at substantially the same temperature so as, in the event ofsaid element overheating, to operate to interrupt or reduce the supplyof electrical energy to the element.

Preferably the control is manually or automatically resettable so thatafter operation it may be reset to allow re-use of the vessel. In oneembodiment, the sensor or actuator may act to trip a spring loadedmechanism of the vessel which may be reset by a user. Preferably thismechanism is such that a user may switch the vessel off by tripping themechanism, and it may comprise for example a lever arm connected to acontrol knob on the outside of the vessel.

In alternative embodiments, at least one of the actuators or sensors maybe of a non-resettable type, for example fusible member, such as aplastics push rod, biased into thermal contact with the base of thevessel and which, in its solid condition maintains closed a sprung setof contacts. When the vessel base overheats the fusible member melts orthermally deforms so as to allow the contacts to open.

Preferably, only two sensors or actuators are provided, and to giveoptimum performance, these are preferably spaced apart through 180°around the vessel base.

Preferably the respective sensors or actuators operate to open sets ofcontacts in the respective poles of the supply to the element, givingdouble pole protection.

Although it would be possible to mount the sensors or actuatorsindependently on the vessel base, in a preferred embodiment they aremounted on a common carrier which is mounted or located to the vesselbase. Such an arrangement considerably facilitates assembly of thevessel. Furthermore, it allows a standard component to be used in adifferent number of embodiments.

The invention also extends to such an assembly and from a second aspecttherefore provides a thermally sensitive control sub-assembly formounting to the base of an electric liquid heating vessel comprising atleast two thermally sensitive sensors mounted to a carrier member atspaced apart mounting locations thereon.

Preferably, the sensors are as described above, most preferably snapacting bimetallic actuators, for example such as those disclosed in GB1542252. These produce a snap action movement when reaching apredetermined temperature, which may then be used either directly orindirectly to open a set of electrical contacts. The movement of theactuators may be transmitted to the contacts via slidable push rods, forexample, or respective pivot members, which may be mounted on thecarrier so as to cooperate with their respective actuators.

The actuators are preferably mounted on the same surface of the carrierto allow them easily to be positioned in good thermal contact with thevessel base.

As stated above, preferably only two actuators are provided, mostpreferably spaced apart by substantially 180°. These actuators maytherefore be mounted at opposite ends of the carrier, which gives goodspatial separation of the actuators and also facilitates good thermalcontact with the element of the vessel, particularly when the element isan annular element, the carrier being mounted within the annulus. Insuch an arrangement, the actuators may then be positioned in closethermal contact with the inner diameter of element, thereby moreaccurately sensing the temperature of the element and improving theoperation of the control.

The carrier is preferably metallic, for example steel, and mostpreferably is a metal plate member. This gives a strong, inexpensive,construction which is both temperature resistant and which can, ifrequired, be metallurgically joined to the base of the vessel by weldingfor example. Alternatively, mounting means such as screws, studs, bossesor the like may be provided on the base to retain the carrier. In afurther arrangement, the carrier may be retained by deforming orcrimping a portion of the vessel base, or the element, over an edge ofthe carrier or even to deform a portion of the carrier itself, forexample to engage in channels or clips provided on the base or element.This avoids the need for secondary operations on the base of the vesselto provide studs or bosses, thereby reducing manufacturing costs.

The carrier may also act to mount, or be integrated with othercomponents, such as boiling controls or electrical connectors for thevessel, such as a "cordless" connector.

In one embodiment, a boiling control is included. The boiling controlmay comprise a thermally sensitive actuator such a bimetallic actuator,more particularly a snap-acting bimetallic actuator as described above,which is exposed in use to vapour produced in the vessel as the liquidboils. The vapour is conveniently directed onto the actuator by a pipeleading into the base compartment, for example through a passageextending from an aperture formed in an upper part of the vessel wall orthrough the vessel base.

The boiling control, or at least the actuator, thereof is preferablyarranged spaced inwardly from the edge of the container, to provide acompact construction. From a yet further broad aspect, the inventionprovides a liquid heating vessel having a liquid receiving container,electrical heating means provided on or in thermal contact with a bottomsurface of said container, and a manually resettable boiling controlarranged in a compartment below said container and spaced inwardly fromthe edge thereof, and means for directing vapour from said vessel tosaid control.

Preferably vapour is directed to the steam control by a flexible pipewhich engages with a steam outlet of the vessel, for example the outletof a pipe extending through the base of the vessel or along a side ofthe vessel. Such an arrangement is advantageous since it allows vapourto be directed to the precise area required, allows tolerances to betaken up between the vessel steam outlet and the control and also allowsthe steam easily to be conducted through a tortuous path, if required.

From a further aspect, therefore, the invention provides a liquidheating vessel comprising a boiling control located beneath the base ofthe vessel, vapour from the interior of the vessel being conducted tothe control through a flexible pipe mounted to a vapour outlet of saidvessel.

From a yet further aspect the invention provides a liquid heating vesselcomprising: a liquid receiving container; an electrical heating elementprovided on or in thermal contact with a base of said container; athermally sensitive overheat control arranged to operate in the event ofsaid element overheating so as to interrupt or reduce the supply ofelectrical energy to the element; and a manually-resettable boilingcontrol operable to interrupt the supply of electrical energy in theevent of liquid in said vessel boiling; said overheat and boilingcontrols being located in a compartment arranged below, andsubstantially within the footprint of the vessel.

The steam-sensitive actuator may be mounted to the carrier and operateto open a set of contacts in the power supply to the element in responseto liquid in the vessel boiling. The steam-sensitive actuator may, forexample be mounted on an arm mounted to the carrier which, if requiredmay be angled to pass over or under the element of the vessel.

Preferably the steam-sensitive actuator is horizontally arranged, and itmay in certain embodiments be arranged under a handle portion of thevessel.

Preferably the steam-sensitive actuator acts to trip a spring-loadedmechanism, such as an over-centre spring mechanism, to open thecontacts. Preferably the spring-loaded mechanism acts to open the samecontacts as those opened by the thermally sensitive control, for examplethrough the pivot members or push rods previously discussed, so as toavoid the need for a further set of contacts. The mechanism must then bereset by a user when it is desired to reboil liquid in the vessel afterliquid in it has boiled.

Preferably the carrier described above is integrated with, or mounts,electrical connector means for conducting electrical power to theelement of the vessel. This could, for example comprise a connectorblock for receiving the wires from a fixed power lead, or a pinconnector for engagement with a socket connector provided in the end ofa disconnectable power lead. Most preferably, however, the carrier isintegrated with a so-called "cordless" connector part which in use willengage with a complementary connector part in a base unit for thevessel.

From a yet further broad aspect, the invention provides a liquid heatingvessel with a liquid receiving container and an electrical heatingelement mounted therein or externally thereof on, or in thermal contactwith the base of said container, a cordless connector arranged generallycentrally of the base, and a thermally sensitive sensor arrangedlaterally displaced from said connector in a base compartment of thevessel, in thermal contact with the base of the vessel.

The invention also extends to an assembly comprising a cordlesselectrical connector mounted on a carrier member, said carrier memberalso mounting at least one thermally sensitive sensor at a locationlaterally offset from the axis of said connector. Most preferably, theconnector is of a type, as described for example in our InternationalPatent Application No. WO 95/08204, which can be engaged with a baseconnector irrespective of their relative angular orientations.

Preferably the connector is arranged between a pair of actuators on thecarrier, so that it can easily be arranged centrally of the base of thevessel.

Preferably the connector comprises an electrically insulating plasticsmoulding mounting a plurality of concentric terminal members. In oneembodiment, the moulding may be secured to the carrier by means of theearth terminal of the connector. This not only provides an earthconnector to the base of the vessel through the carrier, but alsoobviates the need for additional mounting components, thereby reducingproduction costs. In such an embodiment, the earth terminal may be aring member provided with mounting lugs extending from one end thereoffor extending in use from the moulding for engagement with mountingopenings or slots in the carrier. These lugs may be turned down tosecure the connector to the carrier. Alternatively, separate mountingmeans may be provided on the carrier.

Preferably the moulding also mounts one or more sets of switch contactsopenable by the thermally sensitive actuators. In one arrangement, aleaf spring is connected to a respective terminal of the connector andprovides, or mounts, a movable contact of a contact pair, which may beresiliently deflected by a push rod or pivot member previouslydiscussed.

This in itself is a novel arrangement, and from a further aspect,therefore, the invention provides a cordless electrical connector in orfor a electrical appliance said connector having an electricallyconductive strip connected to a terminal of the connector, said stripproviding or mounting an electrical switch contact.

A fixed contact of the contact pair may also be provided on a furthermember mounted in or to the moulding, that further member preferablyhaving connector means, such as a spade connector, for connection to aterminal of the element.

In this way a completely integrated connector and control may beprovided which simply requires mounting to the base of the vessel andelectrical connection to the terminals of the element.

The connection provided on the member for connection to the elementterminal may, as stated above comprise a spade terminal. However toallow different constructional methods to be accommodated, it may alsocomprise a means to receive a connection wire without the need forsoldering or for providing a spade on the wire.

The invention is also applicable to `corded` applications, wherein thevessel comprises a pin inlet in a side wall of the vessel, electricalpower being conducted to the thermally sensitive switch means bysuitable electrical conductors. In view of the high operatingtemperatures which may be experienced in the base compartment,particularly close to the element, it is preferred that such conductorsare conductive strips rather than plastics coated wires which might sagor melt in practice. This in itself is a novel arrangement and from ayet further aspect, therefore, the invention provides a liquid heatingvessel having a liquid receiving container and an electrical heatingelement mounted on or in thermal contact with the underside of saidcontainer, a base compartment below said container and housing switchmeans of a control of the vessel, plug means having terminals forconnection to an external electrical supply, and communicating with theinterior of the base compartment, said terminals being connected to saidswitch means by electrically conductive strips extending laterallytherefrom through the base compartment.

The strips may themselves act as, or mount, a switch contact.

As stated above, the switch contacts of the control of the invention maybe fully opened by a spring loaded trip lever mechanism.

Preferably the trip lever is mounted to a moulding mounted to thecarrier plate. A different moulding may be used for differentapplications, for example corded and cordless applications.

Preferably the trip lever is configured so that when one or other of theactuators of the control operates, a first arm of the lever will bepicked up by a contact or contact mounting member, so as to trip themechanism and thereafter a further arm operates on the contact orcontact mounting member to open the contacts fully.

In one embodiment, a steam sensitive bimetallic actuator may also beprovided on or in the moulding and also act to trip the lever to openthe switch contacts.

A manually operable lever may extend from the trip lever outside thevessel for operation by a user to either trip the mechanism to switchthe vessel off or to reset it once the contact has operated. Preferably,however, two operating levers are provided which in corded applicationsmay be on either side of the electrical inlet to the vessel. This initself is a novel arrangement and will allow for right-handed andleft-handed operating of a vessel, so from a yet further aspect, theinvention provides a liquid heating vessel comprising an electricalheating element, a spring loaded mechanism tripped by operation of athermally sensitive or steam sensitive control of the vessel, and a pairof levers coupled to said mechanism and extending side-by-side outsidesaid vessel for operation by a user to reset the mechanism afteroperation of the control.

As discussed earlier, the preferred element used with the control of thepresent invention is annular, the thermally sensitive control beingarranged radially inside the element. In present constructions of liquidheating vessels, it is normal to provide the element on an aluminiumplate which is secured to and extends substantially completely acrossthe base of the vessel. Furthermore, the element is usually coiled so asto cover over 360° of the base. The result is that, firstly, a largeamount of aluminium is used and, secondly, the heating effect is spreadacross a large proportion of the vessel base resulting in a low wattsdensity. When liquid in the vessel boils, this results in a foaming boilover a large area of the vessel base which not only can be selected fromthe vessel spout and might lift the lid off the vessel. Similarly italso produces less steam for sensing by a steam control. What isrequired is a high watts density for producing convection within thevessel to produce large steam bubbles. This can be achieved by providinga vessel with an element extending through less than 360° on its base.

From a yet further aspect therefore, the invention provides a liquidheating vessel comprising a liquid receiving container, an electricalheating element arranged below, but in thermal contact with thecontainer, and a vapour sensitive control operative in the event ofliquid boiling in the vessel to interrupt the supply of electricalenergy to the element, said element being annular and extending throughless than 360° over the base of the container.

Preferably the element is pre-mounted or embedded in an aluminium ringwhich is then joined to the container base for example, by frictionwelding. This reduces the amount of aluminium used and also concentratesthe heating effect in certain areas of the base.

From a yet further aspect of the invention provides an annular electricheating element for mounting to the base of a liquid heating vessel,said element being embedded in, or mounted to an annular aluminiumsupport member. This allows a pre-produced element to be mounted to avessel base without the need for further operations to be performed onthe element once it is positioned on the base.

Whilst it is known to friction weld aluminium base plates to liquidheating vessels, a further technique may be particularly suitable forthis. In accordance with a yet further aspect of the invention there isprovided a method of joining an aluminium member to the base of a liquidcontaining vessel comprising the steps of subjecting the surface of thevessel base to electron beam texturing in the area to receive the saidmember, and then pressing said member onto said base.

In electron beam texturing, a beam of electrons is fired at the surfaceto produce very small `pocks` in the surface. It has been found thatthese pocks have a re-entrant profile, that is, they increase in areaaway from the surface being treated. This can provide, therefore, aparticularly good key for an aluminium member which can be pressed ontothe base at very high pressure so as to flow into the pocks and beretained thereby.

Some preferred embodiments of the invention will now be described by wayof example with reference to the accompanying drawings in which:

FIG. 1 is a schematic sectional view through a liquid heating vessel inaccordance with the invention;

FIG. 2 is a schematic sectional view along line II--II of FIG. 1;

FIG. 3 shows a control sub-assembly in accordance with the invention;

FIG. 4 shows the sub-assembly of FIG. 3 integrated with a cordlessconnector;

FIG. 5 shows the components of FIG. 4 exploded;

FIG. 6 shows a view on the bottom of the cordless connector of FIGS. 4and 5;

FIG. 7 shows the sub-assembly of FIGS. 4 to 6 mounted on a base plate ofa vessel as seen from below;

FIG. 8 shows an assembly of FIGS. 3 to 7 modified to accommodate a triplever;

FIG. 9 shows a further modification to accommodate a steam control;

FIG. 10 shows a terminal in accordance with the invention;

FIG. 11 shows the strip from which the terminal of FIG. 10 is produced;

FIG. 12 shows a top plan view of further embodiment of the invention;

FIG. 13 shows a schematic, exploded side view of the embodiment of FIG.12;

FIG. 14 shows a bottom plan view of a component of the embodiment ofFIGS. 12 and 13;

FIG. 15 shows a top plan view of a further embodiment of the invention;

FIGS. 16A and 16B show schematic side views of the embodiment of FIG. 15in different operating conditions;

FIG. 17 shows a top plan view of a further embodiment of the invention;and

FIGS. 18A and 18B show schematic side views of the embodiment of FIG. 17in different operating conditions.

With reference to FIGS. 1 and 2 these show a cordless water boilingvessel 2. The vessel 2 comprises a liquid receiving container ofstainless steel, to the bottom of which is attached an aluminium ring 6having a coiled electrical heating element 8 of known construction. Thering 6 is secured to the bottom of the vessel 4 by friction welding orsome other suitable method. For example the bottom of the vessel may bepre-treated by electron beam texturing and the aluminium then pressedonto that part of the vessel bottom.

The element extends around the base for less than 360° and is embeddedin the aluminium ring 6. The aluminium ring 6 has an radially inwardlyprojecting flange 10, against which the bimetallic actuators 12, 14 of athermally sensitive control sub-assembly 16 engage.

The control sub-assembly 16 is integrated with a cordless electricalconnector 18 for the vessel into an integrated unit 19 and is alsoprovided with a steam control 20 as shown schematically in FIG. 2. Thebase of the vessel is also provided with a cover 21.

The unit 19 will now be described in greater detail with reference toFIGS. 3 to 9.

The basic component of the control sub-assembly 16 is a carrier plate 22which is a pressed steel component. The carrier plate 22 has two sideprojections having pairs of arms 24, 26 provided with mounting locations28, 30 for snap-acting bimetallic actuators 12, 14, only one of which isshown in the figures for reasons of clarity. These actuators arebimetallic actuators of the type described in UK Patent 1542252, and aregenerally circular, domed and have a centrally released tongue 32. Uponreaching a predetermined temperature the actuator reverses its curvaturewith a snap action thereby producing an actuating movement. Bothactuators are chosen so as to have substantially similar operatingcharacteristics, say operating at 120° C.

The mounting locations 28, 30 for the respective actuators 12, 14 eachhave a mounting hole 34, 36 to receive a rivet or the like which extendsthrough the tongue 32 of the actuator 12, 14 to secure it in position.

The actuating movements of the bimetallic actuators 12, 14 opensrespective sets of electrical contacts in the supply to the element ofthe vessel through respective pivot members 38 which are mounted inbearings 40 provided in upstands 42 of the carrier plate 22. Again onlyone is shown in the drawings for clarity. The pivot member 38 may bemoulded plastics components, possibly a temperature resistant plasticsmaterial. Each pivot members 38 has a hook-like projection 41 whichabuts a lip 42 of the bimetallic actuator 12 and which has a slot 44 forengagement with a movable contact of a contact pair as will be describedfurther below. A further slot 45 is provided for engagement with anon/off trip lever in certain embodiments, as will be discussed inrelation to FIGS. 8 and 9 below.

The carrier plate 22 has also a number of lugs 44 which may serve asmounting locations for the carrier plate 22 on the base of the vessel.Alternatively, and more preferably, the carrier plate may be mounted tothe base of the vessel at its edges by the aluminium ring being crimpedover the plate at selected locations. FIG. 4. shows the carrier plate 22integrated with a cordless connector 18 of the vessel. The connector 18is of a type as disclosed in our International Patent Application No.PCT/GB94/02010, and is intended to engage with a complementary connectorprovided in a base unit upon which the vessel stands, irrespective oftheir relative angular orientation. As can be seen from FIGS. 5 and 6,it comprises a generally cup-shaped plastics moulding 50 inside whichare mounted a central line pin 52 and an concentric annular neutralterminal 54. These are secured in the base 62 of the moulding 50. Anannular earth terminal 56 is also provided, which lies against the innercircumferential wall 58 of the moulding 50. This terminal 56 has threelugs 60 extending from its upper end which extend through the base 62 ofthe moulding S0.

The base of the moulding 62, is formed with grooves 64, 66 which receiverespective line and neutral terminal strips 68, 70 which make electricalconnection with the pin 52 and ring 54 respectively. The ends 72, 74 ofthe strips 68, 70 mount electrical contacts 76, 78 and are not supportedby the housing so that they may be resiliently deflected by the pivotmembers 38 as will be described further below.

The moulding 50 is also provided with two external pillars 80, 82 whichmount respective terminal strips 84, 86 for connection to the terminals88, 90 of the element. The terminal strips 84, 86 comprise spadeconnector portions 92, 94 and spring clips 96, 98 which engage overpillars 100, 102 in the housing to locate the strips in the moulding 50.The ends 104, 106 of the strips 84, 86 mount fixed electrical contacts(not shown), or may be silver plated for cooperation with the contacts76, 78 provided on the ends of the terminal strips 68, 70. As can beseen from FIG. 4, the pillars 80, 82 have slots 110, 112 to allow theinsertion of the terminal strips 84, 86.

The cordless connector 18, once assembled, is mounted to the carrierplate 22 through the lugs 60 of the earth terminal 66. These lugs 60,align with slots 120 provided in the carrier plates 22 and when insertedthrough the slots the ends of the lugs 60 are turned over to secure theconnector 18 in place, as well as providing a earth contact to thevessel base.

When assembled, the slots 44 in the pivot member 38 engages with thefree ends 72, 74 of the line and neutral strip terminals 74respectively. As can be seen from FIG. 7, the whole assembly can then bemounted to the base plate of a the vessel. In the embodiment shown inFIG. 7, the heating element 8 is mounted in a aluminium plate 6 whichextends substantially completely across the base of the vessel. Theactuators 12, 14 are located at the extremities of the carrier plate 22so as to be positioned closely adjacent the element 8 and thereby beparticularly responsive to the temperature of the element.

In operation, if the vessel 2 should boil dry or be turned on withoutwater in it, the base of the vessel and the element 8 will begin tooverheat. The rise in temperature will be sensed by the actuators 12, 14and when they reach their operating temperature, one or both of themwill reverse their curvature, so as to pivot a respective pivot member38 which will lift the respective leaf spring end 72, 74, therebyopening the contacts in one or both poles of the electrical supply tothe element. When the element vessel cools by a predetermined amount,the actuators 12, 14 will reverse their curvature which will allow thecontacts to remake under the resilience of the leaf springs 68, 70thereby re-connecting the electrical supply to the element. This is thusan automatically resettable system which will cycle until turned off bya user.

FIG. 8 shows an assembly as shown in FIGS. 2, 3 and 7 modified such thatthe actuators must be manually reset to re-connect the electrical supplyto the element 8.

In this embodiment, one end 200 of a trip lever 202 engages in the slot45 in the pivot member 38. Only half of the lever 202 is shown in thedrawings for purposes of clarity, but it is arranged symmetricallyaround the cordless connector 18 and has two arms 204 the ends of whichengage with the respective pivot member 38. The trip lever is pivotallymounted on the carrier plate 22 and has its other end 206 couple to acontrol knob extending from the base of the vessel for manipulation by auser.

The trip lever 202 is provided with a V notch 210 in a tongue 212 whichreceives one end of a C spring (not shown), the other end of whichengages in a V notch 216 in a plate 214 mounted to the carrier plate 22through mounting holes 23 therein (see FIG. 3). This provides abi-stable over centre spring mechanism.

When a bimetallic actuator 12, 14 operates as described above, a pivotmember 38 is lifted to the extent that it lifts an end 200 of the triplever 202 to cause the spring mechanism to go over-centre therebyfurther moving the pivot member 38 with a snap action to open bothcontact sets. This gives a double pole disconnection, even though onlyone of the actuators 12, 14 may have operated. The trip lever 202 isstable in this position and the contacts cannot be re-closed until suchtime as a user resets the mechanism using the lever arm 204, regardlessof the bimetallic actuators 12, 14 returning to their originalconfiguration.

This construction may be further modified to incorporate a steamcontrol, as shown schematically in FIG. 9. In this embodiment a mountingmember 300 mounts a snap-acting bimetallic actuator 19 of a type asdescribed earlier. The mounting member 300 is secured to the carrierplate 22 of the earlier embodiments and is in fact sandwiched betweenthe connector 18 and the plate 22. A lip portion 304 of the actuator 19overlies a cross-web 307 of a trip lever 308, which is mountedsubstantially as described in the previous embodiment. As can be seenschematically in FIG. 2 the actuator 19 is positioned below a steampassage 11 leading from the vessel, so that when liquid in the vesselboils, steam will be exhausted onto the actuator 19 which will reverseits curvature, thereby tripping the lever 308. This will cause both setsof contacts in the control to be opened, to disconnect the power to theelement 8 and they cannot be reclosed, without a user re-setting thelever, as described above in relation to FIG. 8. The actuator 19 ispositioned under the base of the vessel 4, spaced inwardly from the edgethereof.

As shown in FIGS. 1 and 2, the base plate need not extend or be embeddedacross the full face of the vessel, but instead, may be formed as anannular member. In this case as shown in FIG. 1, the bimetallicactuators 12, 14 are mounted in contact with an inwardly facing flange10 of the aluminium ring for good thermal contact with the element. Suchan arrangement saves a considerable amount of aluminium, and alsoproduces a boil within the vessel which will more quickly be sensed bythe actuator to turn the vessel off.

With reference to FIGS. 10 and 11, a preferred terminal 400 inaccordance with the invention is formed from a blank 402 punched from0.25 mm beryllium copper strip.

The terminal has an end 404 having two spring washers 406, which isintended to be supported in a moulding as previously discussed. Theother end of the terminal is formed with a spade terminal 408 and aresilient tongue 410 which is biased back against the opposed floorportion 412 of the terminal end. The tongue is bounded above and below(in the sense of FIG. 10) by flaps 414, 416 folded up form the floorportion 412, and is attached along one edge to the flap 416. The tongue410 is bounded at the front by a plate 420 with a hole 422 to allowaccess to the tongue 410. The tongue is bent back, as shown in FIG. 10,so as to engage resiliently the floor portion 412, so that a wire or thelike may be inserted through the hole 422 and under the tongue 410 so asto be retained. The portion 424 adjacent the floor portion 412 is angledin the direction of introduction of the wire so that while it will allowdeflection of the tongue as the wire is introduced, it will prevent thewire being withdrawn.

An exemplary method of construction of the terminal will now bedescribed with reference to FIG. 11.

Firstly, tongue 410 has its end portion 424 bent back to provide theresilient portion for engagement with the floor portion 412. Then, theflaps 414 and 416 are folded up through 900 from the floor portion 412of the blank. The blank is then folded through 180° along line 428 toform the double thickness spade terminal 400 from the two panels 408a,408b. The plate 420 is then folded through 90° about the line 430 to itsfinal position and finally the two ends of the blank are folded withrespect to each other by 90° about the line 432.

Whilst the embodiments described above use actuators operable atsubstantially the same temperature, it would be possible, if so requiredto meet local safety regulations for example, to have one operate at ahigher temperature than the other.

A further embodiment of the invention will now be described withreference to FIGS. 12, 13 and 14. This embodiment is similar to thatshown in FIGS. 3 to 7, providing protection in the event only that thevessel boils dry or is switched on dry.

As in the earlier embodiment, this control 500 comprises a sub-assembly502 which is integrated with a cordless electrical connector 504.

The basic component of the control sub-assembly 502 is a carrier plate506 which is a pressed steel component. This plate 506 shown from belowin FIG. 14 in more detail. The carrier plate 506 has two opposedmounting locations 508 for respective snap-acting bimetallic actuators510, which are mounted to the side of the carrier plate 506 which isuppermost in use. These actuators are of the type described in relationto the earlier embodiments, and are chosen so as to have substantiallysimilar operating characteristics.

The mounting locations 508, for the respective actuators each have amounting hole 512 to receive a rivet or the like which extends throughthe tongue 514 of the actuator 510 to secure it in position. A window516 is provided around each mounting location 508 to allow movement ofthe actuator to be transmitted through the plate 506.

The carrier plate 506 is integrated with a cordless connector 504 of thevessel. The carrier 506 is mounted on top of the connector, so as to liebetween the base of the vessel and the connector. For clarity in FIG. 15however, since the connector would be below and be obscured by thecarrier 506, the position of the latter is shown in dotted lines. Theconnector 504 is generally similar to that described in FIGS. 2 to 9,comprising a generally cup-shaped plastics moulding 518 inside which aremounted a central line pin 520 and an concentric annular neutralterminal 522. These are secured in the base 524 of the moulding 518. Anannular earth terminal 526 is also provided, which lies against an innercircumferential wall of the moulding 518. The moulding is provided withopposed moulded bores 528, which each slidably receive a push rod 530.The bores 528, are positioned so that the push rod 530 will align with amovable portion of its respective actuator 510.

The moulding 518 is formed on its upper surface with grooves 532, 534which receive respective line and neutral terminal strips 536, 538 whichmake electrical connection with and are riveted to the line pin 520 andneutral ring 522 respectively. Unlike the earlier embodiment, however,the strips 536, 538 extend straight out over an edge of the moulding518. The ends 540, 542 of the strips 536, 538 mount movable electricalcontacts 544, 546 and are not supported by the housing so that they maybe resiliently deflected by the push rods 530 as will be describedfurther below.

The moulding 518 is also provided with two mounts 548, 550 forrespective terminals 552, 554 for connection to the terminals of theelement. The terminals 552, 554 comprise spade connector portions 556,558 and push in connector parts 560, 562 to allow flexibility in themanner of connection to the element. The ends of the terminals 552, 554mount fixed electrical contacts 564, 566, or may be silver plated, andcooperate with the movable contacts 544, 546. As will be seen in FIG.13, the fixed contacts 564, 566 are arranged above the movable contacts544, 546.

The cordless connector 504, once assembled, is mounted to the carrierplate 506 by passing lugs 570 provided on the carrier through openings572 provided in the moulding and turning over the ends of the lugs tosecure the plate 506 and 504 connector together.

The whole assembly is mounted to a vessel base in a similar manner tothe earlier embodiment through mounting holes 574 on the carrier 506, sothat the actuators 510 are in good thermal contact with the base of thevessel. A variety of mounting holes 574 may be provided on the corner toallow for flexibility in mounting locations and arrangements. Themounting is such that the cordless connector lies substantiallycentrally of the vessel base.

In operation, if the vessel should boil dry or be turned on withoutwater in it, the base of the vessel and the element will begin tooverheat. The rise in temperature will be sensed by the actuators 510and when they reach their operating temperature, one or both of themwill reverse their curvature, so as to move its respective push rod 530downwardly in the sense of FIG. 13. This will push the respective leafspring end 540, 542 downwardly, thereby opening the contacts in one orboth poles of the electrical supply to the element. When the elementvessel cools by a predetermined amount, the actuators 510 will reversetheir curvature which will allow the contacts to remake under theresilience of the leaf springs 536, 538 thereby re-connecting theelectrical supply to the element- This is thus an automaticallyresettable system which will cycle until the power to the vessel isturned off by a user.

FIGS. 15 and 16A and 16B show a further embodiment of the invention.This embodiment is a modification of the embodiment of FIGS. 12 and 13to incorporate a boiling control and to allow for manual re-setting ofthe control.

The control 700 shown in FIGS. 15 and 16 comprises a carrier plate 702,which is exactly the same as that in the embodiment of FIGS. 12 and 13,and a cordless connector 704, substantially the same as that shown inthat embodiment. The only significant modification to the connector 704is that its moulding 706 has a lateral `π` like extension 708.

The apex 710 of the extension 708 has a housing 712 for a bimetallicactuator 714 which, as will be described below is exposed to steam fromthe vessel. The top of the housing 712 is provided with a chimney 716over which, in use engages a pipe 718 connected to a steam pipe (notshown) leading from the vessel, for example extending through the baseof the vessel or along an external wall thereof.

The moulding 706 also mounts a spring loaded trip lever 720. The triplever 720 is pivotally mounted in knife edges 722 provided in respectivepillars 724 of the moulding 706, and is spring loaded by an over-centreC spring 726 which engages in respective mountings 728, 730 in the lever720 and moulding 706. At the apex of the trip lever 720, there is a lug732 which engages the bimetallic actuator 714. The other end of thelever is bifurcated and has a number of arms 734, 736, 738, 740 on theend of each bifurcated portion.

The arms 734, 736 are positioned so as to be engageable with therespective terminal strips 742, 744 of the connector 704. When thecontrol is in the `cocked` condition, ie. that shown in FIG. 16A, thearm 736 is positioned just below the terminal strip 742. The arm 734,however, lies over the top of the strip 742, as shown most clearly inFIG. 15.

When a bimetallic actuator 746 operates, it will, as in the earlierembodiment, push a push rod 750 downwardly to open the contacts by asmall amount and thereby interrupt the electrical supply to the elementof the vessel. However, during this downward motion, the strip 742 willengage the arm 736, moving it downwardly by an amount sufficient topivot the trip lever 720 over centre with respect to the C spring 726.This will cause the trip lever to move to the fully open position shownin FIG. 16B, and in so doing, the arm 734 engages with the top of theterminal strip 742 to move it downwardly to give a full 3 mm minimumcontact gap. In order to reset the control, it is necessary to recockthe trip lever by pushing down on the end of the trip lever 720, forexample by a lever attached to the end of the lever and extending out ofthe base compartment of the vessel.

It will be clear that this control will operate irrespective of whichactuator 746 operates in the event of the vessel overheating. It willalso operate if liquid in the vessel boils. In particular, if steam isconducted to the steam actuator 714, and this operates, it will move thetrip lever 720 upwardly through the lug 732 to cause the lever 720 alsoto go over centre, and thus open the contacts by virtue of the arm 734engaging the top of the strip 742.

A yet further embodiment of the invention will now be described withreference to FIGS. 17 and 18A and 18B. This shows a control 800 suitablefor use in `corded` appliances where a pin inlet 802 is provided in awall of the vessel, rather than a cordless connector as in the earlierembodiment.

This embodiment does, however, share a considerable number of commoncomponents with the earlier embodiment. In particular, it uses the samecarrier plate 804 and trip lever 806 as in the earlier embodiment. Inthis embodiment, however, the moulding 808 is different from that in theearlier embodiment. The moulding 808 mounts terminals 810, 812corresponding to those in the earlier embodiment, and also has bores 814to receive respective push rods 816 for engagement with bimetallicactuators 818 as in the earlier embodiment. The moulding 808 is alsomounted to the carrier plate 804 in the same way as earlier described.

The moulding 808 also has a generally `π` shaped lateral extension 822as in the earlier embodiment, and mounts the pin inlet housing moulding802 at its apex.

As in the earlier embodiment, the moulding 802 locates a bimetallicactuator 824 in a housing 826, the housing having a chimney 828 on whichengages a flexible steam pipe 830 which extends around the top of thepin inlet housing 802 to engage with a steam pipe 832 projecting throughthe base 834 of the vessel. A flexible pipe is particularly advantageousin this embodiment, since it allows the steam to be conductedeffectively around the pin inlet in a confined space, as well asallowing production tolerances to be accommodated.

The inlet 802 house line, neutral and earth pins, 836, 838, 840. Theearth pin 840 is connected to an earth spade 844 on the carrier plate804 by a conductive strip 842 rivetted to the pin 840. Current isconducted from the line and neutral pins 836, 838 by respectiveconductive strips 846, 848. These strips 846, 848 run along and areclipped into respective channels 850, 852 provided in the upper surfaceof the moulding 808, and are bent over respective edges 850, 852 so asto be able to deflect at their free ends. Those ends mount respectivecontacts 858, 860 which engage with the contacts 862 provided on therespective terminals 810, 812 to conduct current to the element. Theresilience of the strips 846, 848 will provide a contact pressure in therespective contact pairs.

The trip lever 806 is mounted on the moulding 808 in the same manner asin the earlier embodiment. The lever has the same arm configuration atits free end as in the earlier embodiment, but it is the other two armswhich are used in the operation of the control. In particular, arm 862is positioned to lie under the end of the respective strip 846, 848 andarm 864 is arranged to lie over it. Accordingly when one or otherbimetallic actuator 818 operates in the event of the vessel baseoverheating, the end of the respective strip 846, 848 deflectsdownwardly to break the electrical contact in the contact pair, and inso doing picks up arm 862. This arm is moved sufficiently to cause thetrip lever 806 to go over centre with respect to its C spring, therebycausing the further arm 864 to engage the top of the strip 846, 848 toopen the contacts fully, as in the earlier embodiment and as shown inFIG. 18B. Similarly, when the steam bimetallic actuator operates, itwill also cause the lever to trip, causing both arms 864 to engage withthe respective strip 850, 852 to open the contacts.

To reset the mechanism as in the earlier embodiment, the trip lever 806must be pushed down. This may be done by manipulating levers 870, 872which may be clipped onto mounting spigots 874, 876 on the sides of thetrip lever 806 and which project outside the vessel base, on either sideof the pin inlet 802. Shields 878, 880 may be provided to close theopenings 882, 884 on the vessel side wall through which the levers pass.These levers 870, 872 may be operated to reset the control after it hasoperated or used to trip the lever mechanism if it is desired tointerrupt operation of the vessel at any point during operation.

Whilst it will be appreciated that whilst these embodiments have beendescribed with reference to heating vessels having coiled heatingelements attached to the base of the vessel, the invention also extendsto other types of vessel with base heating, for example vessels havingprinted heating elements provided on their base.

I claim:
 1. An integrated cordless electrical connector and thermallysensitive control unit for mounting beneath a base of a water receivingcontainer of a water boiling vessel, the base being provided with anelectric heating element, the integrated connector and control unitcomprising:a cordless electrical connector of a type engageable with acorresponding connector part irrespective of their relative angularorientation; a pair of thermally sensitive bimetallic actuators arrangedat spaced apart locations on a face of the control unit at respectivelocations each spaced laterally from a central axis of the connector,the actuators being arranged to make good thermal contact with the baseor element such that temperature can be sensed effectively by therespective actuators at spaced apart locations on the base or element inuse; and electrical switch contacts associated with each of theactuators and operatively coupled thereto by respective coupling means,the switch contacts and their associated coupling means being arrangedto a side of the cordless connector, such arrangement being such thatthe actuators can each operate independently of the other in use to openthe associated contacts and interrupt a power supply to the element ofthe vessel when overheating occurs due to the vessel being switched ondry or boiling dry, but neither operates in normal boiling operation ofthe vessel.
 2. A unit as claimed in claim 1 wherein said coupling meanscomprise push rods.
 3. A unit as claimed in claim 1 wherein saidconnector comprises a plurality of concentric terminal members.
 4. Aunit as claimed in claim 1 comprising a plastics moulding mountingcomponents of said connector and said switch contacts.
 5. A unit asclaimed in claim 2 comprising a plastics moulding mounting components ofsaid connector and said switch contacts.
 6. A unit as claimed in claim 3comprising a plastics moulding mounting components of said connector andsaid switch contacts.
 7. A unit as claimed in claim 4 wherein saidbimetallic actuators are mounted on a plate which is mounted to saidplastics moulding.
 8. A unit as claimed in claim 5 wherein saidbimetallic actuators are mounted on a plate which is mounted to saidplastics moulding.
 9. A unit as claimed in claim 6 wherein saidbimetallic actuators are mounted on a plate which is mounted to saidplastics moulding.
 10. A unit as claimed in claim 1 wherein saidactuators are arranged on opposed sides of the connector.
 11. A unit asclaimed in claim 9 wherein said actuators are arranged on opposed sidesof the connector.
 12. A unit as claimed in claim 1 wherein saidactuators operate at substantially a same temperature.
 13. A unit asclaimed in claim 4 wherein said actuators operate at substantially asame temperature.
 14. A unit as claimed in claim 9 wherein saidactuators operate at substantially a same temperature.
 15. A unit asclaimed in claim 1 wherein the respective sets of switch contacts arearranged in respective poles of the supply to the heating element.
 16. Aunit as claimed in claim 1 wherein operation of either actuator opensboth sets of contacts.
 17. A unit as claimed in claim 1 wherein saidactuators operate to trip a spring loaded mechanism which maintains aset of contacts open until reset by a user.
 18. A unit as claimed inclaim 4 wherein said actuators operate to trip a spring loaded mechanismwhich maintains a set of contacts open until reset by a user.
 19. A unitas claimed in claim 9 wherein said actuators operate to trip a springloaded mechanism which maintains a set of contacts open until reset by auser.
 20. A unit as claimed in claim 17 wherein said spring loadedmechanism comprises a trip lever pivotally mounted to said unit andhaving a first arm acted upon in response to operation of said actuatorsto trip the lever, and a second arm for further opening the contactswhen the lever is tripped.
 21. A unit as claimed in claim 1 furthercomprising a manually resettable boiling control.
 22. A unit as claimedin claim 21 wherein said boiling control acts to open the same contactsas one or both of said bimetallic actuators.
 23. A unit as claimed inclaim 22 wherein said boiling control trips a spring loaded mechanismwhich maintains a set of contacts open until reset by a user, saidspring loaded mechanism comprising a trip lever pivotally mounted tosaid unit and having a first arm acted upon in response to operation ofsaid actuators to trip the lever, and a second arm for further openingthe contacts when the lever is tripped.
 24. A unit as claimed in claim23 wherein said boiling control comprises a bimetallic actuator whichacts on an end of said trip lever remote from the said arms acted uponby the thermally sensitive actuators.
 25. An integrated cordlesselectrical connector and thermally sensitive control unit for mountingbeneath a base of a water receiving container of a water boiling vessel,the base being provided with an electric heating element, the integratedconnector and control unit comprising:a cordless electrical connector ofa type engageable with a corresponding connector part irrespective oftheir relative angular orientation; a pair of thermally sensitivebimetallic actuators arranged at spaced apart locations on a face of thecontrol unit at respective locations each spaced laterally from acentral axis of the connector, the actuators being arranged to make goodthermal contact with the base or element such that temperature can besensed effectively by the respective actuators at spaced apart locationson the base or element in use, and operable at substantially a sametemperature; electrical switch contacts associated with each of theactuators and operatively coupled thereto by respective push rodcoupling means, the switch contacts and their associated coupling meansbeing arranged to a side of the cordless connector, such arrangementbeing such that the actuators can each operate independently of theother in use to open the associated contacts and interrupt a powersupply to the element of the vessel when overheating occurs due to thevessel being switched on dry or boiling dry, but neither operates innormal boiling operation of the vessel.
 26. A unit as claimed in claim 5wherein said connector comprises a plurality of concentric terminalmembers.
 27. A unit as claimed in claim 26 wherein said actuators aremounted on a plate mounted to a plastics moulded housing of the unit.28. A liquid heating vessel comprising a water receiving containerhaving a base provided with an electric heating element and anintegrated cordless electrical connector and thermally sensitive controlunit mounting beneath the base of the water receiving container suchthat bimetallic actuators of said unit are arranged in good thermalcontact with spaced apart locations on the base or element, theintegrated connector and control unit comprising:a cordless electricalconnector of a type engageable with a corresponding connector partirrespective of their relative angular orientation; a pair of thermallysensitive bimetallic actuators arranged at spaced apart locations on aface of the control unit at respective locations each spaced laterallyfrom a central axis of the connector, the actuators being arranged tomake good thermal contact with the base or element such that temperaturecan be sensed effectively by the respective actuators at spaced apartlocations on the base or element in use; and electrical switch contactsassociated with each of the actuators and operatively coupled thereto byrespective coupling means, the switch contacts and their associatedcoupling means being arranged to a side of the cordless connector, therespective switch contacts being arranged in respective lines of anelectrical supply to the element of the vessel, such arrangement beingsuch that the actuators can each operate independently of the other inuse to open the associated contacts and interrupt a power supply to theelement of the vessel when overheating occurs due to the vessel beingswitched on dry or boiling dry, but neither operates in normal boilingoperation of the vessel.
 29. A water heating vessel as claimed in claim28 further comprising a base unit for receiving the vessel, said baseunit having, on an upper surface thereof, an electrical connector forengagement with the corresponding electrical connector of the controlunit.
 30. A water heating vessel as claimed in claim 29 wherein saidheating element is a sheathed heating element mounted to an underside ofthe vessel base.
 31. A water heating vessel as claimed in claim 29wherein said heating element is a printed heating element provided onthe vessel base.
 32. An integrated, thermally sensitive, overheatprotection control unit for mounting in thermal contact with anelectrically heated base of a liquid receiving container of a waterboiling vessel, the control unit comprising:a moulded plastics controlbody; a pair of spaced apart, thermally sensitive, resettable, overheatprotection bimetallic actuators arranged at spaced apart locations on aface of the control body for making equally good thermal contact withthe base in use and operable when an element of the vessel overheats dueto the vessel being switched on dry or boiling dry, but not duringnormal boiling operation of the vessel; and two sets of switch contactsprovided in the control body, each set being associated with arespective actuator and openable by its respective actuator when thatactuator operates so as to interrupt a supply of energy to the elementof the vessel, said actuators being intended to operate at substantiallya same temperature.
 33. A unit as claimed in claim 32 wherein saidbimetallic actuators are mounted on a plate which is mounted to thecontrol body.
 34. A unit as claimed in claim 32 wherein said actuatorsare arranged on a peripheral portion of the control unit.
 35. A unit asclaimed in claim 31 wherein said respective sets of contacts arearranged in respective poles of the supply to the element.
 36. A unit asclaimed in claim 31 wherein operation of either actuator opens both setsof contacts.
 37. A unit as claimed in claim 31 wherein said actuatorsoperate to trip a spring loaded mechanism which maintains a set ofcontacts open until reset by a user.
 38. A unit as claimed in claim 37wherein said spring loaded mechanism comprises a trip lever pivotallymounted to said control body and having a first arm acted upon inresponse to operation of said actuators to trip the lever, and a secondarm for further opening the contacts when the lever is tripped.
 39. Aunit as claimed in claim 32 further comprising a cordless electricalconnector for engagement in use with a power supply for the heater. 40.A unit as claimed in claim 32 further comprising a manually resettableboiling control.
 41. A unit as claimed in claim 40 wherein said boilingcontrol acts to open the same contacts as said thermally sensitiveactuators.
 42. A unit as claimed in claim 41 wherein said boilingcontrol trips a spring loaded mechanism.
 43. A unit as claimed in claim42 wherein said spring loaded mechanism comprises a trip lever pivotallymounted to said control body and having a first arm acted upon inresponse to operation of said actuators to trip the lever, and a secondarm for further opening the contacts when the lever is tripped, and theboiling control acts on an end of said trip lever remote from the armsacted upon by the thermally sensitive actuators.
 44. An integrated,thermally sensitive, overheat protection control unit for mounting inthermal contact with an electrically heated base of a liquid receivingcontainer of a water boiling vessel, the control unit comprising:amoulded plastics control body; a pair of spaced apart, thermallysensitive, resettable, overheat protection bimetallic actuators arrangedperipherally on the control unit at spaced apart locations on a face ofthe control body for making equally good thermal contact with the basein use and operable when an element of the vessel overheats due to thevessel being switched on dry or boiling dry, but not during normalboiling operation of the vessel; and two sets of switch contactsprovided in the control body, each set being associated with arespective actuator, arranged in a respective pole of an electricalsupply to the element of the vessel and openable by its respectiveactuator when that actuator operates so as to interrupt a supply ofenergy to the element of the vessel, said actuators being intended tooperate at substantially a same temperature.
 45. A water boiling vesselcomprising a water receiving container having an electrically heatedbase and an integrated, thermally sensitive, overheat protection controlunit, which control unit comprises:a moulded plastics control body; apair of spaced apart, thermally sensitive, resettable, overheatprotection bimetallic actuators arranged peripherally on the controlunit at spaced apart locations on a face of the control body for makingequally good thermal contact with the base in use and operable when anelement of the vessel overheats due to the vessel being switched on dryor boiling dry, but not during normal boiling operation of the vessel;two sets of switch contacts provided in the control body, each set beingassociated with a respective actuator, arranged in a respective pole ofan electrical supply to the element of the vessel and openable by itsrespective actuator when that actuator operates so as to interrupt asupply of energy to the element of the vessel, said actuators beingintended to operate at substantially a same temperature, said unit beingmounted in good thermal contact with an underside of the base of thewater receiving container of the vessel.
 46. A water boiling vessel asclaimed in claim 45 further comprising boiling control means operablewhen liquid in the vessel boils, to interrupt a supply of energy to theelement.
 47. A water boiling vessel as claimed in claim 46 wherein saidboiling control means is a part of the control unit.
 48. A water boilingvessel as claimed in claim 45 wherein the base of the water receivingcontainer is provided with a sheathed heating element extendingcircumferentially thereon, and the control unit is positioned radiallyinwardly of the element.
 49. A water boiling vessel as claimed in claim45 wherein the base of the water receiving vessel is provided with aprinted heating element.